Contour-grinding machine



B. M. w. HANSON.

CONTOUR GRINDING MACHINE.

APPLICATION FILED JULY3I. 19l8.

eT FE H M D m P INVENTOI? M.

B. M. W'. HANSON.

CONTOUR GRINDING MACHINE.

APPLICATION FILEDJULYSi, 191a.

Patented Feb. 1,1921.,

7 SHEETS-SHEET 2.

mm) w W R m Wm M M B. M. W. HANSON. I CONTOUR GRINDING MA'CH INE.

APPLICATION FILED JULY 31, 191B.

Patented Feb. 1, 1921.

INVENTOR M W Him/M7 B. M. w. HANSON.

CONTOUR GRINDING MACHINE.

MENTOR m. w

A ORNE Y B. M. W. HANSON.

' comounenmoma MACHINE.

Patented Feb. 1,1921.

gpmcmou men .IULYSI. 1918. 1,367,382.

' 1 SHEETS-SHEET 5.

INVENTOR @mi/TM. W W

By Arr 'RNEY B.'M. W. HANSON.

CONTOUR GRINDING MACHINE.

1921. {SHEETS-SHEET 5.

B. M. W.,HANSON. CONTOUR. GRIND INGMA'CHINE.

APPLICATION FILED .IULY3I- I918.

Patented Feb. .1, 1921.

ISHEETS--Sl-LEET 7- INVENTOB UNITED .STATES PATENT, OFFICE.

BENG'I' M. W. HANSON, OF HARTFORD, GONILTLECYIIOU''I, ASSIGNOR TO PRATT & WHIT- NEY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

CONTOUR-GRINDING MACHINE.

Specification of Letters Patent.

Patented Feb. 1, 1921.

provide, in a machine of this type, means whereby a non-radial relief may be given to the teeth of a cutter having parts of its con- .tour sharply inclined with respect to the axis. This is accomplished by angularly adjusting the grinding Wheel. "A further object of the invention is to provide certain improved details of construction which increase the-accuracy of the machine and enable it to be operated more conveniently and rapidly. These several objects of the invention will be more fullyapp'arent from the following specification. i

The accompanying-drawings show the embodiment of the invention which I now deem preferable, but it will be understood that numerous changes may be made without departingi from the spirit of the invention as set forth in the claims appended to this specification.

Of the drawings:

Figure 1 is a frontclevation of the machine, certain of the parts being shown in section.

Fig. 2 is a side elevation of the machine,

certain of theparts being shown in section and other parts being broken away.

Fig. 3 is a plan view.. 1

Fig. 4 is a plan view showing the controlling linkage for the wheel and wheel sup- :iort.

1 Fig. 5 is a fragmentary view illustrating the operative relationship between the grinding wheel and the cutter.

Fig. 6 is a fragmentary view showing the wheel and the cutter in another position of relative adjustment.

F ig. 7 is a plan view showing-the vparts 4 appearing in Fig; 5, In this view the wheel and the supporting parts therefor are shown as having been angularly ad usted. 5a

Fig. 8 is a view similar to Fig. 7 but showing the wheel and the supporting parts therefor inanother position of angular adjustment.

Fig. 9 is a fragmentary view showin the indexing stop in a different position of adj ustment from that shown in Fig. 1.

Fig. 10 is a side view somewhat similar to Fig. but showing the wheel dressing mechanlsm in operative position.

Fig. 11 is a fragmentary plan view somewhat similar to Fig. 3 but showing the wheel dressingmechanism in operative positlon.

Fig. 12 is a fragmentary front elevation somewhat similar to Fig. 1 but showing the wheel dressing mechanism in operative position.

Fig. 13 is a fragmentary vertical sectional view showing thedevice for connecting thewheel dressing mechanism with the wheel support. i

Fig. 14 is a view showing a gage for adjusting the wheel dressing tool for wheels of different thicknesses.

Fig. 2' is a diagrammatic view showing the movement which the'wheel dressing tool must have when the point thereof is eccentrio.

Fig. 16 is a view illustrating the adjustment of the operating handle to provide the change of position indicated in Fig. 15.

Fig. 17 is a horizontal sectional view showing the eccentric sleeve for adjusting the wheel dressing tool.

Referring to the drawings, 1 represents the main frame of the ma-chine which is or may be mounted upon a base or pedestal 2 of any desired construction. As more clearly appears in Fig. 4, the frame 1 is in the form of a hollow box or housing-within which are mounted the devices for supporting and controlling the movement of the grinding wheel. These supporting and controlling devices are adapted to permit the wheel to move horizontally in any direction, but they 'hold it in parallelism while being so moved. PreferablyI provide a pantographic mechanism as will be described.

Extending across the top of the frame is a tie plate 3. Interposed between the tie plate 3 and the bottom of the frame is a bearing member 4 which is provided. with two sets of vertical pivots engaging two parallel links 5 and 6. These links extend beneath the tie plate and are pivoted to a cruciform member 7"which is thus mounted for movement forward and backward in parallelism. The cruciform member 7 is provided with two sets of vertical pivots which engage parallel links 8 and 9. These links extend forward through 0 nings in the frame and at their forwar ends are pivotally connected with a plate 10. By means of the pantographic connections which have been described the plate 10 is freely movable horizontally in any direction, but is nevertheless always maintained in parallelism. The grinding wheel is carried by the plate 10 by means of devices to be described and is thus bodily movable with respect. to the cutter or other part to be ground.

Hinged to the main frame 1 at 11 is a bed plate 12. This plate 12 together with the devices carried thereby can be swung upward about the hinge axis to expose the linkage and other parts contained within the housing 1. To the plate 12 are secured the devices which support the cutter or other part to be round.

The mac ine is primarily adapted for grinding cutters with irregular or formed contours such as are used in milling machines, and therefore in referring to the 'work holding parts I will principally confine myself to a description of the elements necessary for holding such a milling cutter. For holding the shank of the cutter to be ground, or for holding an arbor'on which the cutter is mounted, I provide a work spindle 13 which isrotatable in a bearing.

14. As illustrated; there is a cutter A mounted on an arbor B. The spindle can be turned by means of a knurled knob 15 and the spindle can be locked in any desired position by means of the clamping screw controlled by a hand lever 16.

In grinding a toothed cutter it is usually necessary to index the cutter in order that the teeth thereof may be successively resented in proper relation to the grinding wheel. To assist in indexing, I preferably provide a stop mechanism adapted to directly engage the front surfaces of the teeth. As illustrated, this mechanism comprises a stop finger 17 carried by a series of rods 18. 19 and 20 which are adjustably connected and which can-be secured in any desired relative positions by means of clamping screws. The rod 20 is carried by the bearing 14 and can be clamped by means of the clamping screw 21. It will be seen that by means of these several rods the stop 17 is universally adjustable.

Preferably the bearing 14 is carried by a slide 22 which is movable forward and backward under the control of a. screw operated by ahand'wheel 23. Preferably the wheel is provided with graduations, as shown in Fig. 3, whereby the operator. by making use of a ointer 24, can determine the position or t e extent of movement of the slide and of the spindle.

The slide 22 is mounted on a second slide 25 which is movable transversely on ways carried by the plate 12. For moving the slide 25 there is provided a screw operated by a hand wheel 26. Preferably adjustable stops are provided for limiting the movement of the slide 25. As illustrated, these stops are in the form of lock nuts 27 and 28 engaging a rod 29. The rod 29 is adjustable longitudinally but can be clamped 111 any desired position of adjustment b means of a screw 30. Between the nuts 27 and 28 the rod 29 extends through'an aperture in a lug 31 carried by the slide .25, and the nuts by engaging this lug serve to limit the movement of the slide.

Preferably I provide an outboard or tailstock bearin which can be used to support the end of t e arbor B when such an arbor is used. This bearing is in the form of a bushing 32, the central aperture of which fits the arbor. The bushing is mounted in a bracket 33 and can be held in any desired manner. By means of a bolt 34 the bracket 33 is adjustably secured to a slide 35 which is movable forward and backward on the plate 12. The slide can be held in any position of adjustment by means of a bolt 36 engaging a T-slot in the plate.

As I have already stated, the grinding wheel is carried by the plate 10. In accordance with my present invention, there is a grinding wheel supporting bracket 37 which is vertically pivoted to the plate by means of a pivot pin 38. The upper part of the bracket. is provided with vertical ways along which is movable a slide 39. This slide is controlled by a non-rotatable screw 40 wh ch is movable vertically by means of the nut 41. The slide can be clamped in adjusted position by means of a nut 42 engaging a suitable screw. As is'most clearly shown in Fig. 3, the slide 39 is provided with alined horizontal bearings 43 and 44 in which is mounted a spindle 45. For rotating the spindle there is provided a belt wheel 46. A grinding wheel 47 is mounted on the spindle 45 but is readily detachable so that another wheel can be substituted when re quired.

As already stated, the braeket37 is pivotally connected with the plate 10. In order that the bracket may be locked in any desired position of angular adjustment, there is provided ia rod 48 pivoted to the plate 10 at 49. The bracket 37 is provided with-two ears 50 between which there is mounted a yoke5 l which engages the rod 48. By means of abolt 52 the yoke can be clamped against the rod so as to lock thebracket 37 and the associated I parts in any dwired pos1t1on. v

Because of the pantographic linkage which supports the plate 10, this plate together with the bracket and other associated parts are movable freelyin any direction but are maintained in parallelism.- In order that the operator may conveniently move these parts transversely, I provide a sliding rack bar 53 which is suitably guided on the frame 1. This bar is connected with the plate 10 by means of a link 54. A shaft 55 i mountedin a bearing 56 carried by the frame'l, and mounted on this shaft is a pinion 57 which meshes with the rack 53. A hand lever 58 is secured to the shaft 55 for turning it. In this way the bar 53 can be moved longitudinally carrying with it the plate 10 and all connected parts. It is sometimes desirable to disconnect the pinion 57 from the rack, and this can be done'by pushing inward on the hand lever, thus carrying the pinion to the position indicated by dotted lines in Fig. 2. A spring-pressed plunger 59 engaging a groove 60 in the shaft 55 normally serves tohold the pinion in its operative osition.

As shown in i s. 3 and 4 the tie plate 3 is extended at t e front of the machine and is provided with notches adapted to receive projections 61, 61 on a former plate 62 which is used to guide the plate 10'and associated parts as they are moved transversely by means of the hand lever 58. The former is preferably constructed in two sections, there being an auxiliary part 63 which is detachable and which is shaped at its edge to conform to the contour of the cutter to be ground. Occasionally, however, the auxiliary part 63 is not large enough, and in that case a one-piece former is provided having its entire edge shaped as required. For securingthe former there is provided a clamping plate 64 and a clamping screw 65 which extends through anotch 66 in the former.

The bracket 37 carries a former stud 67 which is adapted to engage and cotiperate with the former 62. For securing the former stud 67 the-re is provided on the bracket 37 ahollow boss 68 through which extends a slotted bolt 69.- The bolt extends entirely through the bracket and at the end opposite to the slot is provided with a nut 70. The former stud 67 has an enlarged shank 71 which extends through the slot in the bolt 69 and which engages the end of the boss 68 or engages a washer 72 which is interposed. It will be clear that when the former stud has been put in place, as shown, it can be secured by tightening the nut 70.

In operation a wheel 47 is selected having a width such that it can enter all of the depressions in the cutter and follow all of the grooves of the contour, and a formers stud 67 is selected having the same width as the wheel. For a left-hand cutter such as is shown in Fig. 5, the grinding wheel is ad justed vertically so that its axis lies a suit able distance a below the axis of the cutter, this being effected by means of the screw 40 and the nut 41. Preferably there is a mark 7 0 on the slide 006 crating with a scale 7 0 on the bracket 37 or indicating the extent of vertical movement. This adjustment permits the wheel to cut deeper behind the cutting face of each tooth than at the cuttin face, thus providing the necessary relie For a right-hand cutter the wheel is adjusted so that its axis occupies a corresponding position above the axis of the cutter. Initially, the grinding wheel is positioned with its plane of rotation at right angles to the cutter axis and is held in this position by means of the rod 48. The cutter to be ground is put in place in the way shown. If the cutter has an integral shank the arbor is dispensed with an the shank is inserted directly into the spindle 13. A former 62 is selected which corresponds in contour to the contour of the cutter to be ground, and

this former is clamped in place by means of the plate 64 and the screw 65. By means of the hand wheel 26 and the slide '25 the cutter is adjusted axially so as to bring it into proper relationship with the former.- To bring the cutter and the wheel into operative engagement with each other after the preliminary adjustments have been made, the slide 22 is moved by means of the hand wheel 23. When several cutters of the same kind are to be ground the diameters can be kept uniform by seeing to it that the slide is brought to the same position for each cutter. This can be determined by means of the gradualtions on the hand wheel.

If necessary the right-hand end of the arbor B can be supported by the tailstock or outboard bearing which is adjusted into alinement. This is done first by moving the slide 35 and locking and then by moving the bracket 33 relatively to the slide and clampingrit by means of the bolt 36.

he operator then moves the wheel longitudinally of the cutter at the same time pressing inward to cause the former stud 67 to follow the contour of the former 62?" If necessary, the wheel is moved along the cut= ter several times until grinding of the tooth is completed. Then the cutter is indexed, use being made of the stop 17 to insure the rotation of the successive teethto the same position. It will be understood that for right-hand cutters the stop can be adjusted to engage the faces of the teeth from beneath as indicated in Fig. 9.

The grinding of the cutters in the way thus far described, is satisfactory when there are no sudden variations in diameter; but when there are deep recesses or other irreguinclined toward or away from the axis. the

simple grinding operation set forth does not provide the amount of relief which is desirable for effecting cutting. When the wheel'lies at right angles to the cutter axis the relief is entirely radial, and at points where the contour of the teeth is nearly radial the amount of relief is very small. In accordance with my present invention, I provide means whereby satisfactory relief can be provided for cutters having sudden variations in diameter.

. In the grinding of such a cutter the teeth are first ground in the way already described, with the grinding wheel set at right which could not be eflected with the wheel in lperpendicular position.

ext the wheel is withdrawn and adjusted to a position such as shown in Fig. 8 and the cutter is again adjusted axially to compensate for the incidental axial movement of the wheel. The wheel is again passed over the teeth of the cutter, serving to relieve those parts which are sharply inclined and which are exposed toward the left. It will be noted that the axis of adjustment of the wheel is substantially in alinement with the former stud 67. Therefore the stud is not bodily moved during adjustment and the limits oftravel of the plate 10 and attached parts remain unchanged.-

In order that the cutter may be accurately ground in conformity with the contour of the former, it is necessary for the edge of the wheel to be accurately trued. For properly truing the wheel from time to time, I provide a wheel dressing mechanism which is preferably mounted on the machine. The complete wheel dressing mechanism is shown in Figs. 10, 11 and 12, this being largely omitted from Figs. 1, 2 and 3. When the machine is in normal operation for grinding, the wheel dressing mechanism is thrown back to an inoperative position as shown by dotted lines in Fig. 10.

Extending upward from the plate 12 is a bracket 73 to which is hinged the arm or frame 74 of the dressing mechanism. The arm 74 is mounted on a pin 75 which extends through two lugs on the bracket 73, and the pin is provided with an enlarged head 76 adapted to engage one side of the arm 74. Threaded upon the opposite end of the pin is a nut or knob 77 which can be turned to draw the head 76 against the arm and thus securely clamp the arm in position.

The outer lower end of the arm 74; is provided with a horizontal guideway in which is mounted a slide 78 horizontally movable under the control of a screw 7 9 and a nut 80. Near its rear end the slide 78 is provided with an aperture adapted to receive the reduced end 81 of the aforesaid bolt 69. The part 81 is provided with an annular groove having an inclined wall which is adapted to be engaged by a set screw 82 extending through the slide 78. By tightening the set screw the arm 74 can be securely locked to the bolt 69 and in this way connected with the plate 10 which carries the grimliug wheel. In order that the plate 10 and tin arm 74 may be rigidly held against any accidental play orlost motion I prefer to provide means for locking the bar 53 against movement. As illustrated, this means consists of a set screw 83 adapted to engage the bar. When the set screw is thus engaged the bar is prevented from movement and serves to prevent any transverse movement of the plate 10 or of the arm 7 4. The clamp ing of the arm 7 4 to the bracket 73 by means of the pin 75 and the nut 77, as already described, also assists in preventing such transverse movement. The engagement of the slide 78 with the pin 69 prevents any forward or backward movement of the plate 1 or of the grinding wheel and serves to hold these parts in a forward position with the former pin 67 out of engagement with the former 62.

The arm 74 is provided with a vertical guideway in which is mounted a slide 84 vertically movable under the control of a screw 85 and a nut 86. The slide 84 is provided with a longitudinal horizontal aperture in which is mounted'a sleeve 87 provided with an enlarged collar 88 by means of which it may be manually turned. The sleeve 87 can be clamped in any position of adjustment by means of a clamping screw 89. The sleeve 87 is provided with an eccentric aperture in which is rotatably mounted a shaft 90. Coir nected to or formed integrally with the shaft 90 at its rear end is an offset arm 91 provided with an aperture the axis of which is perpendicular to and in the plane of the axis of the shaft 90. In this aperture is mounted a dressing tool 92, preferably provided with a diamond point. The tool can he held in place by means of a set screw 93 extended through an elongated boss 94. At the front end of the shaft 90 there is connected a hand lever 95 by means of which the shaft lw on the shaft 90 and which is held in adjusted position by means of the nut 99 on a screw extending from the slide 84.

The dressing tool must be adjusted to bring itspoint at the desired distance from the axis of the shaft 90, this distance being, of course, one-half the thickness of the wheel. In order that the dressing tool may be quickly and accurately adjusted, I provide gages of which one is shown at 100 in Fig. 14. The gage can be more conveniently used when the wheel dressing mechanism is in an inoperative position. In Fig. 14 I have illustrated it as swung all the way back. The gage 100 consists of a block having a central aperture ada ted to receive the aforesaid boss 94. rojecting from the block are pins 101, 102 of different diameters, s0 located that their axes can be made to coincide with the axis of the shaft90. A gage is selected having a pin such as 101 corresponding in diameter to the thickness of the wheel. This gage is put in place, as illustrated, and then the dressing tool 92 is adjusted into contact with the surface of the pin. clamped in place by means of the set screw 93 and the gage is removed.

Fig. 5, as has already been stated, shows the relative adjustment of the grinding wheel and of the cutter when the cutter is provided with radial cutting faces. Frequently, however, the cutter is provided with cutting faces which are inclined backward, with respect to the radii, as shown in Fig. 6, such cutters being commonly known as shovel tooth cutters. In the case of such cutters it is necessary to offset the grinding wheel not only through the distance a to provide the desired relief, but also through the supplemental distance 6 corresponding to the distance between the plane of the tool and the parallel radial plane.

As has been fully set forth in my aforesaid copending application, this offset of the wheel through t e distance a causes it to engage the edge of each tooth at a plane which is parallel to but separatedfrom the axis. And in order that the cutter may be properly ground without distortion the wheel must be trued at a plane which is at the same distance fromthe axis.

In order to effect relative adjustment between the grinding wheel at? and the dressing tool 92, use is made of the aforesaid movable slide 78. It will be seen that when this slide is moved toward the rear it carries the grinding wheel with it, thus movingthe axis of the wheel to a position at a distance a. from the plane ofaction of the dressing tool. Preferably there is a scale 103 for indlcating the extent of movement of the slide.

These adjustments having been made, the dressing tool is brought into engagement with the wheel by mov ng the slide 84 by After this adjustment the tool is means of the screw 85 and the nut 86. The

shaft 90 is rocked. slowly back and forth by means of the lever 95, thus swinging the tool 92 in a half-circle and giving the wheel a semi-circular sectional contour in the plane of movement of the tool.

It frequently happens that-the diamond point of the dressing tool 92 is somewhat eccentric so that the limits of movement of the tool must be changed as illustrated in Fig. 15. This is effected by loosening the plate 98 and swinging it to one side or the other to thus move the stop 97.

Obviously the axis of the shaft must :pass through the central plane of the grind- 0 the shaft 90 to bring-its axis into exact 8 coincidence with the central plane of the wheel, use is made of the aforesaid eccentric sleeve 87 The clamping screw 89 is loosened asis also the nut 99 which holds the plate 98. Then the sleeve is free to be turned by 90 means of the collar 88 and the-shaft 90 can be bodily moved until it is brought into coincidence with the central plane of the wheel. Then the clamping screw 89 is tightened and also the nut 99, the plate 98 with the sto 97 having been first properly adjusted, as efore stated.

I do not herein claim as part of my resent invention the structural details 0 the wheel dressing mechanism, as these form the 100 subject matter of my copending application for wheel dressing mechanism, Serial No. 247,636 filed on even date herewith. I do, however, claim as part of my present invention, the herein described tool dressing 1 means combined with the other parts of the machine as set forth in the claims.

What I claim is:

1. The combination of means for supporting a toothed milling cutter having a formed contour, a grinding wheel adapted to engage the face of a tooth of the cutter, and means for supporting and guiding the grinding wheel to cause it to follow the said formed contour and to cut a relief which is non-radial at points where the face of the tooth is inclined with respect to the axis.

2. The combination of means forsuporting a toothed milling cutter having a ormed contour, a grinding wheel adapted of the cutter,

to engage the face of a tooth and means for supportmg and gu ding the grinding wheel to cause it to follow the said formed contour and to cut a relief which is I inclined from the radlal in one d1rect1on or1 '2 5 the other in accordance with the inclination of the face of the tooth with respect to they axls.

3. The combination of a grinding wheell rotatable about a horizontal axis and bodily lfl'o movable horizontally in any direction, means for supporting the grinding wheel and for holding it in parallelism while being moved, and means whereby the wheel may be adjusted on the supporting means about a vertlcal axis.

4. The combination of means for supporting a toothed cutter, a grinding wheel rotatable about a horizontal axis and bodily movable horizontally along the face of a tooth of the cutter, means for supporting the grinding wheel and for holding it in parallelism while being moved, and means whereby the wheel may be adjusted on the supporting means about an axis intersecting the planes of parallel movement.

5. The combination of means for supporting a toothed cutter, a grinding wheel rotatable about a horizontal axis and bodily movable horizontally, means for supporting the grinding wheel and for holding it in parallelism while being moved, means whereby the wheel may be adjusted on the supporting means about an axis intersecting the planes of parallel movement, and a former and former stud for guiding the wheelin ,a fixed path along the face of a tooth of the cutter.

6. The combination of means for supporting a toothed cutter, a grinding wheel rotatable about a horizontal axis and bodily movable horizontally, means for support ing the grinding wheel and for holding it 1 in parallelism while being moved, means whereby the wheel may be adjusted on the supporting means about an axis intersecting the planes of parallel movement, a relatively fixed former,'and former stud on the wheel support cooperating with the former for 40 guidlngthe wheel in a fixed path along the faceof a tooth of the cutter, the axis of the stud being substantially in alinem'ent with the axis of adjustment of the wheel.

7. The combination of means for horizontally supporting a toothed cutter, a grinding wheel rotatable about a horizontal axis and bodily movable horizontally along the face of-a tooth of the cutter, means for supporting the grinding wheel and for holding it in parallellsm while being moved, the wheel being locatedrwith its axis vertically offset from the plane of the front edge of the tooth of the cutter, and means whereby the wheel may be adjusted on the supporting means about a vertical axis.

8. The combination of means for horizontally supporting a toothed cutter, a grinding wheel rotatable about a horizontal axis and bodily movable horizontally along the 610 face of a tooth of the cutter, means for supporting the grinding wheel and for holding it in parallelism while being moved, means fort adjusting the wheel vertically tocause its'axis to be vertically off-set to any desired. extentqfrom the plane of the front edge of the tooth of the cutter, and means whereby the wheel may be adjusted on the supporting means about a vertical axis.

9; The combination of means for support- 1 a toothed cutter, a grinding wheel b ifiily movable along the face of a tooth of the cutter, a support for the grinding wheel, pantographic mechanism for holding the wheel support in parallelism while being moved, and means whereby the wheel may be adjusted on the support about an axis intersecting theplanes of parallel movement.

10. The combination of. a grinding wheel bodily movable horizontally in any direction, means includin a bracket for supporting the grinding w eel and for holding it in parallelism while being moved, means whereby the wheel and the bracket may be adjusted on the supporting means about a vertical axis, a link pivoted to the support, and a clamp on the bracket for engaging the link to hold the wheel in any position of adjustment.

11. The combination of means for rotatably supporting a toothed milling cutter, a grinding wheel adapted to engage and move along the face of a tooth of the cutter, a finger adapted to engage the front of a cutter tooth to determine its position, and an adjustably jointed holder for the finger.

12. The combination of means for rotatably supporting a toothed milling cutter, a grinding wheel adapted to en age and move along the face of a tooth o the cutter, a finger adapted to engage the front of a cutter tooth to determine its position, and a holder for the finger universally adjustable to permit the finger to engage a tooth either at the top or at the bottom. I

13. The combination of a holder for a milling cutter adapted to ermit the cutter to. be turned about its axis, a bodily movable grinding wheel having its axis substantiall parallel to the cutter axis, means, for ho l ing the wheel in parallelism while be1n moved, a former and former stud one fixe and the other movable for guiding the wheel in a fixed path along the surface of the cutter, means for effecting relative adjustment between the cutter holder and the former longitudinally of the cutter axis whereby the position of the cutter and the path of movement of the wheel are properly correlated and adjustable stops for limiting the said longitudinal movement.

14. The combination of means for supporting a toothed cutter, a bodily movable grinding wheel, means for supporting the grinding wheel and for holdlng it in parallelism while being moved, and means for moving the cutter support transversely comprising a slidable rack bar, a linkconnecting the bar with the support, a pinion engaging the rack and a hand lever for turn-v ing the pinion.

15. The combination of means for su porting a toothed cutter, a bodily movab e grinding wheel, means for supporting the grinding wheel and for holding it in parallelism while being moved, and means for moving the cutter support transversely comprising a slidable rack bar, a link connecting the bar with the support, a pinion movable into or out of engagement with the rack and a hand lever for turning the pinion.

16. The combination of a mam frame, means on the main frame for su porting a cutter in fixed position, a grin ing wheel movable along the face of the cutter, means for supporting the grinding Wheel and for holding it in parallelism while being moved, a wheel dressing mechanism pivoted to the main frame and movable to or from an op-.

erative position, means for connecting the grinding Wheel support to the dressing mechanism when the latter is in operative position thus holding the grinding wheel in position to be dressed, and means supplemental to the dressing mechanismfor looking the support against transverse movements.

17. The combination of a main frame,

means on the main frame for supporting a infi wheel and for holding it cutter in fixed position, a grindingwheel movable along the face of the cutter, means for supporting the rinding wheel and for holding it in paralle ism while being moved, a wheel dressing mechanism pivoted to the main frame and movable to or from an operative position, means for connecting the grinding wheelsupport to the dressing mechamsm when thelatter is in operative position thus holding the grindin wheel in position to be dressed, and means %or rigidly clamping the main frame when it is connected to the wheel support.

18. The combination of a main frame, means on the main frame for supporting a contour milling cutter in fixed. position, a grinding wheel movable along the face of the cutter, means for supporting the grindin parallelism le bein moved, and former stu for guiding the wheel in a fixed path, the former consisting of a main part and a detachable auxiliary part having the re uired contour.

dressing mechanism to the,

a former and av n testimony whereof, I hereto aflix my signature.

BENGT M. W. HANSON. 

